The present invention is directed to cooling assemblies and other apparatus used for removing heat from electronic devices. More particularly, the present invention is directed to a thermal dissipation assembly for an electronic device employing a thermoelectric module with multiple arrays of thermoelectric elements of different densities. The multiple arrays of thermoelectric elements allow customization of the cooling capacity of the thermoelectric module when the thermoelectric module is to be coupled to an electronic device, such as an integrated circuit chip, having a non-uniform heat flux across a surface thereof.
As is well known, as the circuit density of electronic chip devices increases, there is a correspondingly increasing demand for the removal of heat generated by these devices. The increased heat demand arises both because the circuit devices are packed more closely together and because the circuits themselves are operated at increasingly high clock frequencies. Nonetheless, it is also known that runaway thermal conditions and excessive heat generated by chips is a leading cause for failure of chip devices. Furthermore, it is anticipated that the demand for heat removal for these devices will increase indefinitely. Accordingly, it is seen that there is a large and significant need to provide useful cooling mechanisms for electronic circuit devices.
Thermoelectric cooling elements operate electronically to produce a cooling effect. By passing a direct current through the elements of a thermoelectric device, a temperature difference is produced across the device which is contrary to that which would be expected from Fourier""s Law.
At one junction of the thermoelectric element both holes and electrons move away, toward the other junction, as a consequence of the current flow through the junction. Holes move through the p type material and electrons through the n type material. To compensate for this loss of charge carriers, additional electrons are raised from the valence band to the conduction band to create new pairs of electrons and holes. Since energy is required to do this, heat is absorbed at this junction. Conversely, as an electron drops into a hole at the other junction, its surplus energy is released in the form of heat. This transfer of thermal energy from the cold junction to the hot junction is known as the Peltier effect.
Use of the Peltier effect permits the surfaces attached to a heat source to be maintained at a temperature below that of a surface attached to a heat sink. What these thermoelectric modules provide is the ability to operate the cold side below the ambient temperature of the cooling medium (air or water) or provide greater heat removal capacity for a given cold plate or component temperature. When direct current is passed through these thermoelectric modules a temperature difference is produced with the result that one side is relatively cooler than the other side. These thermoelectric modules are therefore seen to possess a hot side and a cold side, and provide a mechanism for facilitating the transfer of thermal energy from the cold side of the thermoelectric module to the hot side of the module.
Conventional configurations of large thermoelectric assemblies are nonetheless seen herein to be unnecessarily limiting in terms of their application to the transfer of thermal energy. Thus, while the use of thermoelectric devices is seen to provide a means for the solid state cooling of adjacent electrical devices, their efficiency has been less than optimal.
In addition, complementary metal oxide semiconductor (CMOS) semiconductor processing has progressed to the point where large logic units (such as processors) and their associated control and support circuits (e.g., memory) can today be placed on a single integrated circuit chip. From a thermal view point, this results in a chip with a highly non-uniform heat flux distribution. A relatively high heat flux is generated in the processor core region(s) and a relatively low heat flux is produced in the control/support region(s). In fact, the processor core region heat flux can be as much as 15 times greater than that of the other regions. Thermal paste conduction cooling schemes are not well suited to handle such disparate fluxes. They result in an equally disparate circuit temperature distribution, and more importantly, a much higher absolute junction temperature within the high heat flux regions.
Therefore, to summarize, the present invention provides herein in one aspect a thermal dissipation assembly for facilitating cooling of an electronic device, such as an integrated circuit chip. The thermal dissipation assembly includes a thermoelectric assembly or module which is configured to couple to a surface of a heat generating component, such as the electronic device. The heat generating component has a nonuniform thermal distribution across the surface thereof between at least one first region of the surface and at least one second region of the surface, wherein the at least the one first region has higher heat flux than the at least one second region. The thermoelectric assembly includes at least one first area of thermoelectric elements and at least one second area of thermoelectric elements. The at least one first area of thermoelectric elements is configured to at least partially align over the at least one first region of higher heat flux when the thermoelectric assembly is coupled to the surface of the heat generating component, and the at least one second area of thermoelectric elements is configured for at least partial alignment over the at least one second region of lower heat flux when the thermoelectric assembly is coupled to the surface of the heat generating component. Further, the at least one first area of thermoelectric elements has a greater density of thermoelectric elements than the at least one second area of thermoelectric elements.
In another aspect, an electronic module is provided which includes an electronic device having a non-uniform thermal distribution across a surface thereof between at least one first region of the surface and at least one second region of the surface, wherein the at least one first region has higher heat flux than the at least one second region. The module also includes a thermoelectric assembly coupled to the surface of the electronic device. The thermoelectric assembly includes at least one first area of thermoelectric elements and at least one second area of thermoelectric elements. The at least one first area of thermoelectric elements is aligned over the at least one first region of higher heat flux, and the at least one second area of thermoelectric elements is aligned over the at least one second region of lower heat flux. Further, the at least one first area of thermoelectric elements has a greater density of thermoelectric elements than the at least one second area of thermoelectric elements.
In a further aspect, a method of fabricating a thermal dissipation assembly for an electronic device is provided. The method includes: providing a thermoelectric assembly configured to couple to a surface of an electronic device, the electronic device having a non-uniform thermal distribution across its surface between at least one first region of the surface and at least one second region of the surface, wherein the at least one first region has a higher heat flux than the at least one second region; and wherein the providing of the thermoelectric assembly includes providing at least one first area of thermoelectric elements and at least one second area of thermoelectric elements. The at least one first area of thermoelectric elements is configured for at least partial alignment over the at least one first region of higher heat flux when the thermoelectric assembly is coupled to the surface of the electronic device, and the at least one second area of thermoelectric elements is configured for at least partial alignment over the at least one second region of lower heat flux when the thermoelectric assembly is coupled to the surface of an electronic device, and wherein the at least one first area of thermoelectric elements has greater density than the at least one second area of thermoelectric elements.
To restate, provided herein is a thermal dissipation assembly employing a thermoelectric assembly or module having multiple arrays of thermoelectric elements with different densities. The thermoelectric assembly is useful in cooling a heat generating component, such as a integrated circuit chip. A thermoelectric assembly in accordance with an aspect of the present invention allows handling of high heat flux zones on a component, while cooling the entire component to acceptable temperatures, thereby establishing a more uniform temperature distribution on the component. This advantageously facilitates integrated circuit design and operation. Additionally, the thermoelectric assembly presented establishes lower circuit temperatures for a given heat load, and employs a lower power consumption in achieving the desired cooling, i.e., provides a more efficient cooling approach.
Additional features and advantages are realized through the techniques of the present invention. Other embodiments and aspects of the invention are described in detail herein and are considered a part of the claimed invention. For a better understanding of the invention with advantages and features, refer to the description and to the drawings.